For manufacturing of metal sheets used as exterior décor panels for home appliances, there are various methods of forming a pattern to provide surfaces of the metal sheets with aesthetic effects, such as film attachment, printing, etching, rolling, and the like.
Among the aforementioned methods, in the case of rolling using a roller provided with a convex stereoscopic pattern, when a metal sheet passes through a rolling apparatus, a stereoscopic pattern is formed at a front surface of the metal sheet.
FIG. 1, for example, illustrates a method of forming a pattern at a front surface of a metal sheet by rolling the front surface. As shown, a metal sheet 1′ having a fine stereoscopic pattern at a front surface thereof is manufactured by rolling a metal sheet 1″ using a rolling apparatus 300 including an upper roller 310 provided with a rolling mold 200 and a lower dummy roller 320 supporting the metal sheet 1″. Considerably great rolling pressure within a range of about 1 ton to 10 tons is vertically applied from the upper roller 310 and the lower dummy roller 320 to the metal sheet 1″ to be rolled.
In the above-described rolling apparatus 300, the upper roller 310 provided with the rolling mold 200 is positioned to face the front surface of the metal sheet 1″ to form a stereoscopic pattern on the front surface of the metal sheet 1″ by rolling. In this case, no pattern is formed at a rear surface of the metal sheet 1″ because the lower dummy roller 320 located to face the rear surface of the metal sheet 1″ is not provided with a pattern.
As illustrated in FIG. 1, a thickness of the metal sheet 1′ having passed through the rolling apparatus 300 is visibly reduced so as to be distinguished by the naked eye because considerably great rolling pressure of about 10 tons is applied to the metal sheet 1″. For example, in order to provide the rolled metal sheet with a thickness of about 0.60 mm, an original thickness of the raw metal sheet may be about 0.63 mm.